Daikin FTKM-U Series Service Manual page 42

Control Specification
4. Determine prohibited frequency
When starting the compressor, the frequency is initialized according to the D value of the
Initial Frequency
indoor unit.
D signal: Indoor frequency command
The difference between the room thermistor temperature and the target temperature is taken as
the D value and is used for D signal of frequency command.
 OFF = Thermostat OFF
PI Control
1. P control
2. I control
3. Frequency control when other controls are functioning
4. Upper and lower limit of frequency by PI control
38
There is a certain prohibited frequency such as a power supply frequency.
D
Temperature Temperature
difference signal
OFF
–2.0
–1.5 1
–1.0 2
–0.5 3
D value is calculated in each sampling time (20 seconds), and the frequency is adjusted
according to its difference from the frequency previously calculated.
If the operating frequency does not change for more than a certain fixed time, the frequency
is adjusted according to D value.
When D is low, the frequency is lowered.
When D is high, the frequency is increased.
 When frequency is dropping:
Frequency control is carried out only when the frequency drops.
 For controlling lower limit:
Frequency control is carried out only when the frequency rises.
The frequency upper and lower limits are set according to the command of the indoor unit.
When the indoor unit quiet operation command comes from the indoor unit, the upper limit
frequency is lower than the usual setting.
D
Temperature
difference signal difference
0 4
0.5 5
1.0 6
1.5 7
D
Temperature
signal difference
2.0 8 4.0
2.5 9 4.5
3.0 10 5.0
3.5 11 5.5
Part 4 Functions and Control
SiMX042215E
D
signal
12
13
14
15